The discovery of a spectrum of slow earthquakes and slow slip events on many of Earth’s major tectonic faults has sparked a revolution in the fields of seismology, geodesy, and fault mechanics. Until about 15 years ago, it was believed that faults either failed rapidly in damaging earthquakes or by creeping at rates of plate tectonic motion. However, the widespread observation of episodic, slow fault slip events at plate boundaries around the world, including at subduction zones, has revealed that fault slip behavior spans a continuum of modes, from steady creep to fast, earthquake-inducing slip. Understanding the processes that control these various failure modes is one key to unlocking the physics of earthquake nucleation and slip on faults. Scientific ocean drilling holds a unique place at the forefront of these efforts by allowing direct access to fault zones and sediment in the subsurface where slow slip events occur, by enabling near-field monitoring in borehole observatories, and by providing samples of incoming sedimentary succession that comprises the protolith for material in slow slip source regions at subduction zones. Here, we summarize fundamental contributions from scientific ocean drilling at subduction zones to this emerging field.

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